††††††††††† There are several items that need improvement and they should become part of a new teamís objectives:

1.      Improve the center of gravity of the arm by using lighter components and moving heavy objects, such as the motors, further down in the arm.The use of belts has been examined in the past and was found to be rather expensive, but this would greatly reduce the center of gravity of the arm.

2.      Make the arm lighter by selecting lighter materials and components or further redesigning the arm.

3.      Investigate other ways to draw power off of the two twelve volt batteries.This year, both batteries were wired in series to get the 24 VDC, but all of the current was drawn off of the grounded battery.This caused this battery to drain at a high rate.



††††††††††† This yearís team tried to be consistent with motor selection to simplify controls and design.This idea seemed to work very well and should be improved upon in the future.The goal should be to use as many of the same motors as possible.Also, DC motors should be the focus of study for the future teams because they tend to be very compatible with the controls and the wheelchair.




††††††††††† This yearís gripper design worked fairly well, but there are several things that could be changed for improved performance.The first problem is that the gripper is extremely long.This is not necessarily a problem in operation, but it looks awkward.Another thing that the gripper has trouble with is small objects.Fixing this problem would require a complete redesign of the fingers and palm.Another suggestion is to somehow attach a hooking device to open things such as drawers and cupboards.



††††††††††† For the next academic year, the Gateway team may want to look into controllers other than the OOPic.Although the OOPic is very convenient to use in some respects, it does have some shortfalls.First, there are other chips available now that are much faster than the chip on the OOPic.Most of the controllers with these chips would need to be programmed in the assembly programming language, which is not as desirable.Also, the OOPic should be able to handle all of the necessary calculations, but there are some problems in getting the OOPic to do all of the math properly.The control system durability should also be improved by eliminating large pulse-width-modulation amplitudes on lower rated motors (i.e. not using 12 volt motor control boards with 2.4 volt motors).Another suggestion is to implement a control code that is able to run the arm only when the wheelchair is turned off.




Table of Contents

Section 10: Controls

Appendix A